Ellipsograph



March 17., 1970 K. A. HILL 3,500,544

ELLIPsoGRAPH Filed Jan. 25, 1968 4 Sheets-Sheet 1 @Mm of?. @4m AMQM, non @4W March 17, 1970 K, A, Hl| 3,500,544

ELLIPSOGRAPH Filed Jan. 25, 19.68 4 Sheets-Sheet 2 Mvsmwomd 5| 9(2Z 319-102 7' d-r-rgmsv-/j March 17, 1970 K. A. H|| 3,500,544

ELLIPSOGRAPH Filed Jan. 25, 1968 4 Sheets-Sheet 3 K. A. HILL March 17, 1970 ELLIPSOGRAPH l 4. Sheets-Sheet 4 Filed Jan. 25, 196s United States Patent O ABSTRACT F THE DISCLOSURE A compass for drawing ellipses and circles of any desired proportions and of anydesired size within a given range includes a marking element carried on the Vfollowing the movement of a cross slide mounted forcrosswise shifting on a main slide and movable longitudinally with the main slide. The longitudinal and crosswise components of motion of an eccetrically mounted and rotatable driving pin are transmitted to the cross slide through a proportioning device to move the cross slide and the marking element through longitudinal and crosswise strokes. Adjustment of the eccentricity of the driving pin causes the length of both strokes of the cross slide to change simultaneously and by equal amounts to change the size of the geometrical figure being drawn. The proportioning device is adjustable independently of the driving pin and may be set to transmit any selected fraction of the crosswise component of the driving pin to the cross slide to vary the crosswise stroke of such slide without changing the longitudinal stroke and thereby enable adjustment of the proportions of the gure.

Background of the invention This invention relates to an ellipsograph for drawing ellipses and circles. More particularly, the invention pertains to an ellipsograph of the type which may be adjusted to draw circles viewed from any angle and of any desired size -between a point and a maximum size circle for which the instrument is designed. An ellipsograph possessing these capabilities is disclosed in Meyer et al. Patent 2,810,962. Other types of ellipsographs are disclosed in Irick Patent 2,494,557 and Hancox Patent 2,996,804.

Summary of the invention The present invention aims primarily to provide a new and improved ellipsograph capable of Vperforming more functions with greater ease of adjustment and operation than has been possible with prior instruments of the same general type. Otherimportant objects of the invention are to provide an ellipsograph capable of drawing concentric ellipses of varying sizes by making only one simple adjustment to the instrument; to provide an ellipsograph with which circles and ellipses may'be divided into any number of accurate sections; and to provide an ellipsograph capable of drawing radial lines in a circle or ellipse and capable of constructing center lines.

The invention also resides in the ease with which the ellipsograph may be adjusted to form ellipses of different sizes or proportions; in the novel construction of the instru- -ment permitting arrangement of the operating elements in a compact, attractive and relatively inexpensive package; and in the unique mounting of various elements of the instrument to compensate for wear and to insure accurate production of the iigures even after repeated service use of the ellipsograph.

Other objects and advantages will becomes apparent as the following detailed description proceeds with reference to the accompanying drawings. y

Brief description of the drawings l FIG. 1 is a perspective view of a new and improved 3,500,544 Patented Mar. 17, 1970 ICC ellipsograph embodying the novel features of the present invention.

FIG. 2 is a plan View of the ellipsograph shown i'n FIG. 1 with parts broken away for puiposes of clarity. FIG. 3 represents a graphical construction of an ellipse and .illustrates some of the principles of the present in vention. i Y FIG. 4 is an enlarged fragmentary plan view of the-ellipsograph with parts broken away'and'shown in section. FIG. 5 is a fragmentary cross-section taken 'substantially along the line 5-5 of FIG. 4

FIG. 6 is a view similar to FIG. 4 but showing parts in moved positions.

FIG. 7 is a fragmentary cross-section taken substantially along the line 7 7 of FIG. 4. J

FIG. 8 is an enlarged fragmentary cross-section taken substantially along the line 8-8 of FIG. 4. l f

FIGS. 9 and l0 are diagrammatic views schematically showing the ellipsograph during successive steps of'drawing a circle.

FIGS. 11 and l2 are views similar to FIGS. 9 and 10 and schematically showing the ellipsograph during successive steps of drawing an ellipse.

Description of the preferred embodiment As shown in the drawings for purposes of illustration, the invention is embodied in an elipse compass or illipsograph 15 especially suitable for use by draftsmen and artists for drawing circles and ellipses of various sizes and proportions. The geometrical figures are traced out and formed by a marking device 1'6 which is moved across the drawing paper in accordance with a predetermined function to describe the desired figure. As is true of some prior instruments, the present ellipsograph may be adjusted to cause the marking device to draw circles ranging upwardly from a small dot or point to that size of circle produced when the instrument is set at maximum capacity. In addition, the ellipsograph may be set to develop ellipses from any circle within the range when viewed from any angle from to 0 thereby enabling the drawing of a full range of ellipses varying from a true circle to a straight line.

In its primary aspect, the present invention contemplates mounting the marking device 16 on a slide 17 movable bodily in a first path with another slide 18 and movable in a second path relative to the latter slide. One component of motion of a manually rotatable actuator 19 is transmitted to the slide 17 to move the marking device in the general direction of the iirst path, and a second component of motion of lthe actuator is transmitted to the slide 17 to move the marking device in the general direction of the second path. Provision is made not only for varying the components of motion transmitted to the slide 17 simultaneously and by proportional amounts tocontrol the size of the iigure being drawn but also for varying one component of, motion independently of the othe'rto control the proportions of the figure being drawn. 'With such an arrangement, the ellipsograph vis much easier to use and is simpler to adjust to draw figures of various sizes and proportions than prior devices of the same general type and, at the same time, is capable of performing la greater number of operations thereby signicantly increasing its versatility and usefulness. Y

More speciiically, the slides 17 and 18 are mounted on a base comprising a base plate 20 and a cover plate 21. The base plate is flat and generally rectangular inA configuration and is formed with a straight rear edge 23 and straight side edges 24 to facilitate use of the ellipsograph with conventional drafting equipment such as straight edges, drafting machines, protractors and the like. Near its forward edge, the base plate is formed with two forwardly projecting and horizontally spaced legs 25 defining between-the mean-- open spa device 1'6 may move during the drawing of geometrical figures. The forward edges 26 of the two legs are straight and are conveniently used to center.the ellipsograph on one'center line of theellipse or circlevbeing drawn. In this instance, -theffront edges 26 of: the legs 2S locate the ellipsograph relative to the center line of an exemplary ellipse e or circle c shown in FIG. 1, such center line being disposed perpendicular topthe legs and lying-` along the front edgesl 2-6. The spacedv Aapart projecting 'legs enable accurate locating of the instrument while still allowing movement offthe markingA device; into 'close proximity with the mainbase plate20, thereby reducing the` extent offprojection ofA thepmarking de-,viceqf-rornV thel base plate and.contributing to compact design-of., the ,ellipsograph Herein, the cover plate 21 is shaped as an inverted-dishr and. is fastened in overlying ,relation with the Abase, plate 20 -todeiine a lhollow enclosure within which they slides,

17and 18 are housed.The. cover plate may be made ,of decorative wood or plasticand servesto prevent damage to the operating elements of the instrumentand,to-protect the` elements from vdust and other -foreign matter which otherwisemight impair the efliciency or accuracy of the instrument.

As shown most clearly in FIGS. 4, 5 and 7, the slide 18, which `will be referred to as a main slide, is simply a flat rectangular plate disposed on the upper side of the base plate 20 and guided on the latter for back and forth sliding in a rectilinear path extending generally fore-andaftV of the ellipsograph. Such guiding is effected by a pair of laterally spaced and longitudinally extending parallel rails 27 and 29 fastened to the upper side of the base plate and each formed along its inboard side with an elongated laterally opening groove. Rollers 30 depending from the corners of the main slide 18 and journaled to turn about upright axes are formed with lower flanges 31 (FIG. 5) which lit and ride within the grooves to mount the slide forl accurately guided and relatively friction free back andv forth movement. t

Advantageously, one of the guide rails, herein the rail 29, vis mounted for bodily floating toward and away from the other rail 27 and is spring-loaded toward such rail to apply sidewise pressure to the rollers 30 and eliminate anyrlooseness or play in the action of the main slide 18 that might develop as a result of wear. For this purpose, each end portion of the rail 29 is slidable laterally beneath a flange 33 (FIG. 4) formed on a bracket assembly 34 fixed to the base plate 20, and is urged toward the rail 27 by a reversely bent strip 35 of spring metal formed integrally with the bracket assembly and embedded in the end of the rail. The springs 3S maintain the rail 29 in intimate contact with the adjacent pair of rollersand, at the same time, cause pressing of the other pair of rollers against the rail 27 to compensate for wear and to pre-V serve accurate guiding of the main slide during the service life'of the instrument. v l

The slide 17, hereafter called the cross slide, is shaped as a -cruciform and includes a pair of cross arms 36 extending laterally from a rearwardly projecting head 37 and a forwardly projecting stem 3'9,.the latter extending forwardly through an opening in the frontwof the cover plate 21 and being disposed in overlying relationwith the openuspace defined between the legs 25. The cross slide 17 "is'movable back and forth with -the main slide 18 in the'longitudinal path followed by the latter slide and, in addition, is guided for independent crosswise or lateral .translation on the main slide in a `second rectilinear ce within'whichthe marking- 4 -side of nthefforward -rail 40 while an identical roller 44 is rotatably mounted on the lower side of the head 37 to roll along the rear side of the rear rail 41. To eliminate looseness in the action of the cross slide, the rear rail 41 is mounted for floating-toward and away from the forward raili 40 and'is springeurgedaway' from'thedatter to press against there'r' rollr 44'and to d'ravvthe forward rollers Asintb, cena "jwitirfhefqrtvrja-ran, ,strewn in Profit; the, n airig'., meinung .is achieved wlnrnnged clamps 45 anchored to the..m. air'1 slide 1S and receiving the 4rearrail 41 for back and forth sliding. Coiledfcompression springs 46 are telescoped into holes in the farward side of the rear rail' 41 adler'against the rear side of the frontrailiijltl,toiturgethe "'fe'arailrearwardly, the front rail being anchored rigidly on thel upper sideof .the mainslidebyscre l V4T FIG' and thereby move the--lattcr-e-inea fore-and-aft or longitudinally extending p atlrthrough@` strokeequal in length vto that of the mai slide. At the''Sametir'n,I ,the rails .4 0 and 41 positively,guide ythe cross'slide fQriiidependent I lateral or sidewise movementjr'elative t themainslide path extending across and perpendiculai to the longitudil across the forward portion of the main slide. -Flanged rollers 43 similar to, the rollers 30'project downwardly from the 36 0f the cross slide and rifle along the ,forwald along a transverse path extending perpendicular to' the longitudinal path.` Thus, the cross slider/is free to transf late inmutuallyy perpendicular directions lvvithinma single plane but is constrained against rotation. i, 'Y

Fol'lowing'the movement 'of the, cross slide `17 fand carried on the free vend of the steml 39 is the marking device 16 -which 'herein comprises a self-contained ink cartridgel 49 (FIG. l) `with a scriber in the for-rn of a ball point 50 although any other type of pen, pencil or s 'criber could be used equally well. The cartridge is clamped between the jaws of a springftype holder 51 vwhich is attached to the forward endl of a spring metal strip 53 cantilevered at its rear end to the underside of thestem 39 by screws 54. The bight portion of a horizontal U-shaped yoke 55 is sandwiched between the stern and the spring strip 53 and flexes the latter downwardly to press the scriber 50 against the drawing paper as long as a vertical U-shaped yoke orlever 56 is disposed in anupright posif tion as shown in FIG. 1. The lever 56 is pivoted on the stem 39 as indicated at 57 and includes a pair of depending ears 59 to which the legs of then horizontal lyoke'are fastened. When the lever is rocked rearwardly labout the pivots 57, the horizontal yoke 55 is shifted forwardly-to relievethe loading on the spring strip 53a and to allow the scrib'er 50 to movejupwardly from the Y'paper under theurgingofthestrip.A l n v y, lAsa vresult of following the longitudinal Land crosswise movements of the cross slide 17, the s criber 50'A is capable of-makingithe"motions requiredlt'o ldraw r circles and ellipses.fAs"specilically described thus far, however, the instrumentlacksthenecessary control for moving the Iscribe'r in'ia predeterminedl pattern as' dictated by the particular circle or 'ellipse' beingi' drawn. Basically,` such control iseife'cted herein by the actuatorv 19"which"is manually operable to'mo've the slides17 and18` and by a proportioning vdevice or proportion'erv 60E whchis'conected between the ctuat'or'nd'theslides to'tansmit the Imotion "of thev actuator-'tothe slides-in' accordance with a selected function." Y 'A In general, the actuator 19 'comprises a 'circula'rdisc or dial'61 'mounted inv the top/of the"cove`r plate 21 for rotation about anupr'ight `axis t. The .'dial y61 tswithin a circular opening v63 (FIG. -8)formed-in the cover platewith the upper surface of thedialfb'ing vliush with the upper surface of the plate. As vshoivn in 4FIGS54 and 8, `three brackets 64 are fastened byscrews '65 :to 'the underside of the cover plate and serve tojournalthree rollers 66 spaced angularly and equally-around the open-v ing y6.3 and formed withdiang'es 67 "interlittingV within groovfefextending around the peripheryf'of the dial. The, rollers thus support the dial and alsoestablish anti-fric:

tion rolling surfaces between the dial and the cover plate. Preferably, one of the brackets 64 is pivotable about its mounting screw 65 and is urged toward the dial by a spring strip 69 anchored to a screw 70 on the cover plate and pressing against the bracket to prevent looseness from developing between the rollers and the dial. A knob 71 (FIGS. l and 7) offset radially from the axis of rotation and projecting upwardly from the dial may be rotated to turn the latter relative to the cover plate.

The actuator 19 further comprises' a driving member or pin 73 rotatable in a circular path about the axis t of the dial 61 and connected to the proportioner 60 to move the latter and the slides 17 and 18 in response to rotation of the dial. As shown in FIGS. 5 and 7, the driving pin 73 projects downwardly from the dial and is telescoped with a rotatable fit into a bore formed axially through a at-head screw 74` Upper and lower square clamping discs 75 are fitted slidably but non-rotatably onto the screw 74 and are located within an elongated rectangular slot 76 formed throughthe dial and extending radially from the axis t. The clamping discs are spaced vertically from each other, with the edges of the dial alongside the slot being sandwiched between the two discs. When an operator nut 77 threaded on the upper end of the screw 74 is tightened, the two discs are drawn together and clamp the side edges of the slot to lock the screw and the driving pin 73 in a fixed radial position within the slot. Loosening of the nut frees the clamping discs to allow sliding of the driving pin in the slot and toward and away from the axis t to different radial positions thereby to change the eccentricity or throw of the pin and the amount of motion transferred to the proportioner 60 in response to rotation of the dial. The pin may be shifted in the slot by gripping the loosened nut and pushing or pulling the same in the desired direction.

In this instance, the proportioner 60 includes a generally diamond-shaped frame formed by pairs of long and short strips 79 and 80 (FIG. 4) defining alined front and rear corners 81 and 83 and alined side corners 84, the included angle between the strips 79 and 80 preferably being 90. 'Ihe proportioner overlies the main slide 18 and the cross slide 17 and is formed at its rear corner 83 with a vertically extending hole into which the lower end portion of the driving pin 73 is threaded as shown in FIG. 7 to connect the pin to the proportioner. As the dial 61 is rotated counterclockwise from the position shown in FIGS. 1 and 4, the driving pin 73 'moves longitudinally and rearwardly with a rst component of motion y (FIG. 4) in the generaldirection of the path of the main slide 18 and also moves crosswise to the left with a second component of motion x in a perpendicular direction. The crosswise displacement of the pin becomes maximum and the crosswise component reverses in direction when the piu is rotated through 90 and 270 while the longitudinal displacement becomes maximum and the longitudinal component reverses when the pin is rotated through 180 and 360. Both components of motion of the pin are transmitted to the proportioner 60 -which moves accordingly and in turn transfers the longitudinal component to the cross slide vthrough the main slide and transmits the crosswise component directly to the cross slide. f

Transfer ofthe longitudinal component of motion of the driving pin 73 through the proportioner 60 and to the main slide 18 is effected by a set of guide members 85, 86 and 87 (FIG. 4) in the form of rails mounted on the upper side of the main slide. The rails 85 and 86 extend generally crosswise of the main slide beneath the proportioner strips 79 and just in front of the two side corners 84. The rail 87 extends across the rearportion of the main slide is positioned j ust rearwardly of the rear corner 83. A flanged roller -89 (FIG. 7) projecting downwardly from the rear corner 83 and journaled on the lower end of the driving pin 73 rides along a groove in the front side of the rearrguide rail 87 while similar 6 rollers 90 depending from the side corners 84 ride along the rear side of the front rails 85 and 86. Advantageously, the rear guide rail 87 is mounted for back and forth oating and is urged toward the front rails by spring brackets 91 identical to the bracket assemblies 34 mounting the side rail 29.

As the driving pin 73 is rotated and moves the proportioner `60 rearwardly and to the left, the rear roller 89 bears against the rear rail 87 to shift the main slide 18 and the cross slide 17 rearwardly. When the proportioner is moved forwardly, the front rollers 90 bear against the front guide rails 85 and 86 to shift the main slide and the cross slide in a forward direction. The cross slide is moved in each direction through a distance equal to twice the radial spacing between the driving pin 73 and the axis t or is moved through a total back and forth longitudinal stroke equal in length to the diameter of the circular path followed by the pin 73 each time the latter is turned through one revolution. Only the longitudinal component of motion of the driving pin 73 and the proportioner 60 is transmitted to the main slide since, during the time the proportioner is being moved forwardly and rearwardly, it simply moves crosswise across the main slide and rolls along the guide rails 85, 86 and 87 to avoid imparting the crosswise component of motion to the main slide.

To transmit the crosswise component of motion of the driving pin 73 and the proportioner 60 to the cross slide 17, a lost-motion connection including a driven pin 93 (FIGS. 4 and 7) depending from the front corner 81 of the proportioner is projected downwardly into a longitudinally extending slot 94 formed through the stem 39 of the cross slide. The pin 93 pivots and slides within the slot and bears against the side edges thereof to transfer the crosswise component of the proportioner to the cross slide and move the latter laterally along the guides 40 and 41. Thus, for each revolution of the driving pin 73, the cross slide normally is moved laterally in each direction through a total crosswise stroke of a length determinable by the radial spacing of the driving pin 73 from the axis t and determinable as a function of the diameter of the circular path followed by the pin. Because of the sliding connection between the driven pin 93 and the cross slide 17, the longitudinal component of motion of the -proportioner 60 is not transferred to the cross Slide through the pin 93 but instead is transmitted to the cross slide only through the guides to 87 and the main slide 18. Looseness between the driven pin 93 and the slot 94 is prevented by forming a resilient bearing surface along the side -edges of the slot with a hairpin spring 95 (FIG. 4) whose head is looped around a screw 96 on the stem 39 and whose legs are held in a transverse slot 97 formed in the slide head 37 beyond the rear end of the slot 94.

With the foregoing arrangement, true circles of any size within a range from a small dot or point to a circle with a three inch diameter, the maximum circle for which the present instrument is designed, may be drawn as long as the proportioner guides 85 and 86 extend perpendicular to the main slide 18 and parallel to the rear guide 87 as shown in FIGS. 4, 9 and l0. The diameter of the circle drawn is dependent upon the radial positioning of the driving pin 73 in the slot 76 with respect to the rotational axis t of the dial 61. For example,when the driving pin is adjusted radially inwardly within the slot to a position in which its axis coincides exactly with the axis t, rotation of the dial by the knob 71 produces no longitudinal or crosswise components of motion of the pin with the result that neither of the slides 17 and 18 is shifted to cause moving of the scriber 50. When the nut 77 is loosened and the driving pin 73 shifted outwardly in the slot to a position spaced some distance outwardly from the axis t, turning of the dial will rotate the pin about the axis with finite longitudinal and crosswise components of motion to move the proportioner 60 and driving pin 73 is increased, the longitudinal and cross- Wise components increase equally and by amounts corresponding to the increase in such Spacing to cause the drawingof av circle with a larger diameter. A s eries of calibrations 99 (FIG. 2) are formed`, on the dialf61, adjacent ,oneV side ,of the slot 76 and cooperate with nindex infla'rl: 100rscribed on the upper clamping disc 75 to enable easy `visual determination ofthe radial spacing ofl the pin-73 from the axis t and ofthe diameter of Athe circle whichjheinstrurnentis set top'draw. lSuitable indicia varying from zeroto ,three inches lmay be printedfalong'- side' the,calibrationsfwith ,theA actual 'spacing between successive ones of the calibrated vmarks being equalt'o lone ,Y half4 the numerical .difference :between the Vv"corresponding indicia. L

l .Let ,i'tb asfsliirned,thatit'isdesired to use the ellipso graph,y 15,; to'draw aftru'e 'fcircle, c; (FIG.A 10) `with a maximumjdiam' of three 'inches andv that the center' lines cl, clf for'. such circle khave been constructed vony thelvdra'w'- ing paperasshownin FIGS` 9and l1 0 to locate'the center of the circle. Afterthe driving pin 73' has been adjusted inwardly, to the, zero'sposition in the slot 7.6 and into coincidence with the axis t, the ellipsograph isv centered with respect to the center lines by placing the instrument on the paper with the front edges 26 of the legs 25 lying along the center line cI and with the scriber 50 located directly at thevintersection of the two lines. Thereafter, the nut 77 is loosened and the driving pin 73 is adjusted outwardly in the slot 76 until the index mark 100 registers with the three inch mark on the calibrations 99, such adjustment normally taking place with the scriber held upwardly from the paper by the yoke 55. After the nut 77 has been tightened to lock the driving pin 73 in the slot and after the scriber has been lowered, the dial 61 is simply turned through one complete revolution to cause the scriber to draw a three inch circle.

During turning of the dial 61, through one revolution, the driving pin 73 moves rearwardly with a three inch longitudinal stroke and then forwardly with a three inch longitudinal stroke. In addition, the pin is moved crosswise to the left and the right with a three inch stroke in each direction. The motions of the pin are transmitted it is desired to draw the line r.Y After the nut 77 has been to the proportioner 60 which, as long as the guides 85 and 8-6 are positioned perpendicular to the main slide 18 as shown in FIGS. 4, 9 and 10, simply moves rearwardly, forwardly, to the left and to the right in accordance with the movement of the pin while remaining disposed at all p times in the angular position shown in FIG. 4. The forward and rearward movements of the proportioner are transmitted to the -main slide through the guides 85 to 87, and the main slide acts'through the guides 40 and 41 to cause back and forth movement of the cross slide 17 and the scriber through a total longitudinal stroke of three inches. At the same time, the proportioner moves crosswise along the guides to 87 and acts through the driven pin 93. toV transfer its crosswise component of motion directly to the cross slide 17 thereby to move the l latter and the scriber sidewise through a total stroke of three inches. Accordingly, the circular motion of the driving pin 73 Ais simply transferred to the scriber through the proportioner and the slides to move the scriber in a circular path corresponding to that of the pin thus resulting in the drawing of a perfect circle with a diameter of three inches. Changingl of the diameter of the circle may be effected merely by shifting the pin 73 to a different radial position in the slot 76 to change simultaneously and by equal amounts the longitudinal and crosswise u stroke undertaken by the scriber when the dial is rotated. Advantageously, the'above-described arrangement enables the drawing of radial lines r (FIGS. 2 'and 3) from the arc of the circle to its center and permits division of the arc into any number of accurate sections. To draw radial lines, rotation of the dial 61 is stopped with the scriber 50 positioned on the arc at the point from which loosened, the pin 73 simply is shifted inwardly in the slot 76 until the axis t is reached.Such inward shifting of the pin acts through the proportioner 60 and the main slide 18 and produces compound movement of the cross slide 17 to draw the scriber inwardly in adirection parallel to the directionfof shiftingv of the lpin thus causing the drawing of a radus of thefcircle. Radiimay bedr-awa at any angle on the' circle bylcha'nging the angularvposition of the dial before again shifting the pin 73 inwardly. It will be ireadily apparent thatthe center lines of a circle may be constructed by 'shifting the"pin inwardly`f1jom four successive positions spaced from each other.

Division of the arc yof the` circleinto sections is also achieved by shifting the pin 73 inwardlyV except that the latter need`=be shiftedfonly a slight distanc'e'to cause the scriber 50wtol draw a short mark across the arc oflthe circlezTo` facilitatesuch division land aIso the drawin g of radii `.a,t the f desire'd angle, the dial 61 is formed on'itfs peripheryf'withy auseries of Aanglllladrly'spaced calibrat ns vor,marks10A-l calibratedlin degrees and eoactin'g with, an yindex mark 103 toindicate 'the` angular position of the pinr73 and the"s c'riber V50, the index mark ,103 being formed on althinl ring 104 fastened to thecover plate 21'and ericirclingthe dial. If desired, a similarly calibrated set 105 of degree'marks maybe formed on the ring 104 to cooperate with an" index pointer 106 formed on the dial 61. v

ln carrying out the present invention, means are providedfor selectively causing the transfer to the cross slide 17 of any selected fraction of one component of motion (herein, the crosswise component) of thedriving pin 73 in order to change the length of the crosswise stroke of the vslide 17 independently of the length of the longitudinal strokeand thereby enable the drawing of acircle of any size from any viewing angle so that true elipses of various sizes and proportions may be produced. In this instance, these meanscomprise a pair of angularly adjustable arms 107 and 109 (FIG. 4) which may be considered as part lof the lguides 85 and 86 and which mount such guides for adjustment to selected angular positions to cause rocking of the proportioner 60 about the pins 73 and 93 when the dial 61 is rotated thereby resulting in a change in the proportion of the crosswise component of motion of the pin 73 transferred to the cross slide and the scriber 50.

More vspeciiically, the arms 107 and 109 are rigid with and underlie the guides 85 and 86, respectively, and are mounted for angular swingingabout upright axes bypivot screws. 110 (FIG. 6) fupstanding from the main slide. Preferably, the spacing between the screws 110 is exactly the same as the spacing between the -side` rollers 90 on the proportioner 60 in order to enableangular adjustment of the guides without bindin-g but while' keeping the rollers in intimate contact `with the guides in all positions. With this arrangement, the rollers will not shift the guides 85, 86 angularly when the proportioner is moved and lalso the proportioner, whenlin lthe position Vshown in FIG. 4, will not shift when'the guides are adjusted. i li 'f Attheir inboard ends, the two arms 107 and 109 are formed with gear sectors'108'meshing withl one another to cause the arms and the guides 85 and 86 to turn in unison by equal amounts but in opposite directions when one of the arms is swung about its associated pivot screw 110. The guides are capable of turning from the position shown in FIG. 4, in which the guides are in a straight line and extend parallel'to the guide 87, to the position shown in PIG. 6 in which the guides delinea forwardly openingV with its apex facing the guide l87. In the present ellipsograph and When'the angle between each set of the frame strips 79 and 80 `is 90, the angular displacement undertaken by the guides in moving between the straight position (FIG. 4)- and the extreme V- position (FIG.'6) is approximately 35. For ellipsographs of different sizes, the extreme V-angle mayvary. The

geometry of any size arrangement should be such that, when the guides are in the extreme V-position, the driven pin 93 is located at the intersection of imaginary lines extending through the pivot screws 110 and extending perpendicular to the guiding surfaces of the guides 85, 86.

To move the guides 85, 86 between the straight and V-position, a cam follower 111 formed on the outboard end of the arm 109 rides against the perpiheral surface of a cam 113 rotatable about an upright axis and programmed to swing the arms through an equal angle for each identical increment of rotation of the cam. One revolution of the cam from the position shown in FIG. 4 to that shown in FIG. 6 swings the arms through their entire range of 35 with a pair of stop surfaces 112 and 112 (FIG. 4) on the cam periphery engaging the follower 111 to limit rotation of the cam to 360 in each direction. Contractile springs 116 stretched between ears 117 on the arms 107 and 109 and screws on the main slide 18 press the follower against the surface of the cam and also urge the teeth of the gear segments 108 together to prevent backlash.

As shown most clearly in FIG. 5, the cam 113 is fastened by a screw 114 to the lower end of an operating knob 115 which is telescoped over and rotatable on an upright bolt 118 anchored to the main slide 18 and projecting upwardly through the cover plate 21 through an elongated slot 11811 (FIG. l) formed in the cover plate to accommodate movement of the bolt and the knob with the slide 18. A disc 119 is fitted within a depressed well on the upper side of the knob 11S and is pressed between the head of the bolt 118 and the upper end of a tubular bushing 120 telescoped over the bolt 118 so that the disc 119 remains stationary Awhen the knob 115V is rotated to turn the cam 113.

To explain the basic manner of forming ellipses with the present ellipsograph, let it be assumed that it is desired to draw an ellipse e (FIGS. 3 and 12) with a major axis a of three inches and with a minor axis b of 11/2 inches, such an ellipse being a development of a three inch circle when viewed at an angle of 45. First, the instrument is centered on the center lines of the ellipse as explained above in conjunction with the drawing of a true circle, and then the pin 73 is shifted to the threeinch position in the slot 76 to establish the length of the major axis of the ellipse. Assuming that the guides 8S and 86 are disposed in their straight positions shown in FIGS. 4 and 9, rotation of the dial 61 would result in the drawing of a true three inch circle c with the full crosswise component of motion of the pin 73 being transmitted to the cross slide 17 through the proportioner 61 and with the latter simply remaining oriented as shown in FIGS. 9 and 10 and undertaking no rocking movement during rotation of the dial.

To adjust the instrument from drawing a circle c to drawing an elipse e with a 11/2 minor axis, it is necessary only to turn the cam 113 with the knob 115 through one half revolution to cause the guides 85 and 86 to turn upwardly from their straight positions to V-positions (FIG. 11) midway between the extreme positions shown in FIGS. 4 and 6. Now, as the dial 61 is rotated, the cross slide 17 will move forwardly and rearwardly with the same three inch stroke as before but the inclined guides will cause the proportioner 60 to rock back and forth about the pins 73 and 93 as the proportioner moves crosswise along the guides, the proportioner rocking clockwise about its center as it moves to the left and rocking counterclockwise as it moves to the right. One half of the crosswise component of the driving pin 73 is lost or absorbed due to the rocking of the proportioner and, as a result, only one half of the crosswise component is transmitted to the cross slide to move the latter and the scriber 50 through its crosswise stroke.

Accordingly, one revolution of the dial 61 produces a three inch longitudinal stroke of the scriber 50 but only a 11/2 inch crosswise stroke thereby resulting in the drawing of a mathematically perfect ellipse e with a major axis a of three inches and a minor axis b of 11/2 inches. To increase the dimension of the minor axis without changing the major axis, the knob 115 is simply turned to swing the guides 85, 86 rearwardly thereby to reduce the rocking action of the proportioner 160` and to cause the transmission of a greater percentage of the crosswise cornponent to the cross slide. A decrease in the length of the minor axis may be effected by turning the knob to increase the inclination of the guides and to decrease the percentage of the horizontal component transferred to the cross slide. When the rails are inclined in the extreme positions shown in FIG. 6, the proportioner undertakes a maximum rocking action and simply pivots about the driven pin 93 without transmitting any of the horizontal component of motion of the driving pin 73 to the cross slide. As a result, rotation of the dial 61 simply moves the scriber 50 rearwardly and forwardly to draw a perfectly straight line of three inch length, such line representing a three inch circle viewed at an angle of Thus, both the major and minor axes are adjusted by equal amounts when the radial position of the pin 73 is changed. Turning of the knob changes the length of the minor axis but does not affect the longitudinal cornponent transferred to the cross slide 17 and thus does not change the length of the major axis.

Determination of the proportions of the ellipse or of the relative length of the minor axis is facilitated by Calibrating the knob 115 in equal increments varying from 0 to 90 as indicated at 121 in FIG. 2, the 0 mark registering with `an index mark 123 on the stationary disc 119 when the guides 85 and 86 are straight to cause drawing of a true circle and the 90 mark registering with the index mark when the guides are inclined fully to cause the drawing of a `straight line. Thus, the operator of the ellipsograph may conveniently determine when the knob has been turned to set the guides to cause drawing of a circle at a desired viewing angle. Alternatively, the knob may be calibrated in terms of percentages ranging from 0 to 100 to enable the setting of the minor axis as a certain proportion of the major axis.

From the foregoing, it will be apparent that -adjustment of the diameter of a circle or equal adjustments of the major and `minor axes of an ellipse to control the size of the gure maybe achieved simply by changing the radial position of the pin 73 in the slot 76. The ultimate length of the minor axis and the proportions of an ellipse are determined by the inclination of the guides 85 and 86 as controlled by the setting of the operator knob 115. By simply leaving the knob 115 set in a xed position and by adjusting the pin 73 to different positions within the slot between successive revolutions of the dial 61, a complete set of concentric ellipses with axes of the same proportions may be drawn without the need of making more than one `adjustment to the instrument. In addition, radial lines may be drawn in the ellipse, and the periphery thereof may be divided into sections by shifting the pin 73 in the slot. When such shifting occurs with the guides set at an inclination, the scriber 50 will not parallel the movement of the pin 73 but will move along a line d (FIG. 3) which represents the equivalent radius r of a similar angular division on a true circle. Thus, the ellipsograph is extremely simple to use and adjust and is capable of performing a large num-ber of drawing operations.

I claim as my invention:

1. In an ellipsograph, the combination of, a base, a main slide guided for back and forth translation on said base, a cross slide movable back and forth with said main slide in a first rectilinear and substantially horizontal path and guided on said main slide for translation relative to the latter in a second rectilinear and substantially horizontal -path extending crosswise of lsaid first path, a marking element carried on and following the movement of said cross slide, a manually turnable actuator journaled on said base to rotate about an upright axis and carrying a driving member normally spaced radially from said axis and rotatable in a circular path about said axis, a proportioning device connected to said driving member and normallyl mov-able with a first component of motion in the general direction of said first path and with a second component of motion in the general direction of said second path as an incident to rotation of said actuator, a set of guides on said main slide and transmitting the first component of motion of said proportioning device to said main slide to move the latter and said cross slide along said first path through a first back and forth stroke proportional in length to the diameter of said circular path in response to rotation of said driving member -through one revolution, said guides mounting said proportioning device for movement relative to said main slide in the direction of said second path thereby to leave the proportioning device free to move in such direction without transmitting said second component of motion to said main slide when said driving member is rotated, a connection between said proportioning device and said cross slide and operable in response to rotation of said driving member `through one revolution to transmit said second component of motion to the cross slide to move the latter along said second path through a second back and forth stroke of a length determinable as a function of the diameter of said circular path, means mounting said driving member adjustably on said actuator and enabling `selective movement of said driving member toward and away from said axis to permit changing of the diameter of said circular path and the length of said first and second strokes, and means mounting at least one of said guidesfor selective adjustment to various angular positions on said main slide to cause the transmission of different selected. fractions of said second component of motion to said cross slide and thereby enable changing of the length of said second stroke independently of the .radial positioning of said driving member and lwithout changing the length of said first stroke.

2. An ellipsograph as defined in claim 1 in which said base comprises a base plate and a cover plate overlying said base plate, said main slide being guided on said base plate, and said actuator comprising a disc journaled in said cover plate with said driving member depending from said disc and connected to said proportioning de- VlCC.

3. An ellipsograph as defined in claim 2 in which one of said disc and cover plate is formed with angularly spaced calibrations enabling determination of the angular position of said driving member.

4. An ellipsograph as defined in claim 2 in which said means adjustably mounting said driving member includes a radially extending slot formed through said disc, said driving member comprising a pin slidable along said slot, and means for locking said pin at various fixed positions along the length of said slot.

5. An ellipsograph as defined in claim 4 further including, a series of calibrations` formed on the upper side of said disc and spaced along said slot, and an indicator movable radially with said pin and along said calibrations to enable visual determination of the radial position of said pin. y

6. An ellipsograph as defined in claim 2 in which said base plate is formed with a pair of spaced legs disposed in the plane of and projecting from said base plate and defining between them an open space, said cross slide `having a portion overlying said open space with said marking element depending from said cross slide and movable within said open space.

7. A11 ellipsograph as defined inclaim 1 in which said actuator comprises a disc journaled for rotation on said l base and formed with a radially extending slot, said driving member comprising a pin extending axially of said disc and connected t0 said proportioning device, said pin being guided by and selectively slidable along said .slot and acting through said proportioning device to impart movement to said cross slide in a direction determined by the direction of sliding of said pin and the angular positioning of said guides.

8. An ellipsograph as defined in claim 1 in which said connection between said proportioning device and said cross slide is a lost-motion connectionftransmitting said second component of motion of said proportioning device to -said cross slide without transmitting said first lcomponent of motion to said cross slide.

9. An ellipsograph as defined in claim 8 in which Said lost-motion connection comprises a pin and slot connection between said proportioning device and said cross slide, said slot being elongated and extendingbgene'rally in the direction of said first path. i I p' j 10. An ellipsograph as defined in claim 1 in which` said set of guides comprises first and second guide members mounted on said main slide and spaced from each other along said first path, Vsaid proportioning device ,including means engageable with said guide members toitransniit said first component of motion of said proportioning deviceto said mainV slide and said cross slide and movable along said guide members to prevent the transmissionof said second component'of movement to said main slide.

11. An ellipsograph as defined in claim 10 in which said first guide member extends perpendicular to said first path, said second guide member extending crosswise of said second path and being angularly adjustable to selected positions between a first-position extending perpendicular to said first path `and a second position spaced approximately thirty-five degrees from said first position.

12. An ellipsograph as defined in claim 11 in which the entire second component of motion of said proportioning device is transmitted to said cross slide when said second guide member is in said first position and in which none ofthe second component of motion of .saidproportioning device is transmitted to said cross slidewhen said second guide member is in said second position.

13. An ellipsograph as defined in claim 1 in which said set of guides comprises-a first guide memberrextending perpendicular to said first path, and second k,and third guide members spaced alongrsaid first path from saidL first guide member and extending generally crosswise of said first path, said second and third guide members each lbeing mounted for angular adjustment on said main slide, and means engageable with one of said second and third guide members and selectively operable to adjust the second and third guide members angularly in unison by equal amounts butin opposite directions.

14. An ellipsograph as defined in claim 13 in which said second andthird guide members yare mounted-for turning about spaced upright axes and arepositioned-endto-end, the opposing ends of such guide members being geared together whereby turning of one such guide member results in equal but opposite turning of theother such guide member. Y

15. An ellipsograph as defined in claim 14 further including a cam follower carried on one of said second and third guide members, and said engageable means comprising a cam mounted for rotation on said .base and engageable with said follower toturn said` second and third guide members. f v,

16. An ellipsograph yas defined inclam 14 in which said second and thirdguideV members are.,turnablerf,rom positions extending perpendicular to said first path to :positions forming a V with its apex facing said first guide member.V l

17. An4 ellipsograph as defined in claim 13 inrwhichsaid proportioning device includes a generally diamond` shape frame having alined front and rear corners and having alined side corners, a-roller on eachof said side corners engageable with and movable along one edge of said sec ond and third guide members, and an additionalroller on said rear corner and engageable with and f movable along one edge ef said first guide member.

18. An ellipsograph as defined in claim 17 in which said driving member is fastened to the rear corner of said proportioning device, said connection between said cross slide and said proportioning device being located at the front corner of the proportioning device.

19. An ellipsograph as defined in claim 17 in which said second and third guide members are mounted for turning about spaced upright pivot axes and are positioned endto-end, the horizontal distance between said pivot axes being substantially equal to the horizontal distance between the rollers on the side corners of said proportioning device to maintain such rollers riding along said second and third guide members in all angular positions of the latter. v

20. An ellipsograph as defined in claim 1 in which'said set of guides includes first and second guide members mounted on said main slide and spaced from eachy other along said first path, one of said guide members being mounted for fioating toward and away from the other guide member, and resilient means acting on said one guide member and urging the latter in the direction of said first path.

21. An ellipsograph as defined in claim 20 further including first and second spaced apart guide rails extending across said main slide and said first path and mounting said cross slide for movement in said second path, one of said guide rails being mounted for floating toward and away from the other guide rail, and resilient means acting on said one guide rail and urging the latter in the N direction of said first path.

22. Au ellipsograph as defined in claim 21 further including first and second guide elements extending along said base and along said first path and mounting said main slide for movement in such path, one of said guide elements being mounted for floating toward and away from the other guide element, and resilient means acting on said one guide element and urging the latter in the direction of said second path.

23. An ellipsograph as defined in claim 1 in which said set of guides comprises a first guide member extending perpendicular to said first path, and second and third guide members spaced along said first path from said first guide member and extending generally crosswise of said first path, straight guide surfaces on said second and third guide members engageable with said proportioning device for guiding the latter, said second and third guide members being mounted for turning on said main slide about spaced upright pivot axes between first and second extreme positions, and said connetcion being located at the intersection of two imaginary lines which extend through said pivot axes and substantially perpendicular to said guide surfaces when said second and third guide members are disposed in said second extreme position.

24. In an ellipsograph, the combination of, a base, a main slide guided for back and forth translation on said base, a cross slide movable back and forth with said main slide in a first rectilinear path and guided on said main slidje for translation relative to the latter in a second rectilinear path extending crosswise of said first path, a marking element carried on and following the movement of said cross slide, a manually turnable actuator journaled on said base to rotate about an axis and carrying a driving member normally spaced radially from said axis and rotatable in a circular path about said axis with a first back and forth component of motion in the general direction of said first path and with a second back and forth component of motion in the general direction of said second path, means connecting said driving member to said main slide for transmitting said first component of motion of said driving member to said main slide to move the latter and said cross slide along said first path through a first back and forth stroke corresponding generally in direction to the back and forth movement of said first component of motion and proportional in length to the diameter of said circular path in response to rotation of said driving member through one revolution, means connecting the same said driving member to said cross slide and normally operable in response to rotation of said driving member through one revolution to transmit said second component of motion of said driving member to the cross slide to move the latter along said second path through a second back and forth stroke corresponding generally in direction to the back and forth movement of said second component of motion and of a length determinable as a function of the diameter of said circular path, means mounting said driving member adjustably on said actuator and enabling selective movement of said driving member toward and away from said axis to permit changing of the diameter of said circular path and the length of said first and second strokes by proportional amounts, and means selectively adjustable to cause the transmission of any selected fraction of said second component of motion of said driving member to said cross slide and operable to change the length of said second stroke independently of the radial positioning of said driving member and without changing the length of said first stroke.

25. An ellipsograph as defined in claim 24 in which said actuator comprises a disc journaled for rotation on said base and formed with a radially extending slot, said driving member comprising a pin extending axially of said disc and connected to said cross slide, said pin being guided -by and selectively slidable along said slot and being operable when slid back and forth in the slot to impart' movement to said cross slide to move said marking element toward and away from said axis in the same general direction as the direction of sliding of said pin.

26. In an ellipsograph, the combination of, a base, a main slide guided for back and forth translation on said base, a cross slide, a first set of guides mounting said cross slide for movement back and forth with said main slide in a first rectilinear path and guiding said cross slide on said main slide for translation relative to the latter in a second rectilinear path extending crosswise of said first path, a marking element carried on and following the movement of said cross slide, a manually turnable actuator journaled on said base to rotate about an axis and carrying a driving member normally spaced radially from said axis and rotatable in a circular path about said axis, a proportioning device connected to said driving mem- 1ber to pivot relative to said actuator and normally driven with a first component of motion in the general direction of said first path and with a second component of motion in the general direction of said second path as an incident to rotation of said actuator, a second set of guides on said main slide spaced along said first path from said first set of guides and transmitting the first component of motion of said proportioning device to said main slide to move the latter and said cross slide along said first path through a first back and forth stroke proportional in length to the diameter of said circular path in response to rotation of said driving member through one revolution, said second set of guides mounting said proportioning device for movement relative to said main slide in the direction of said second path thereby to leave the proportioning device free to move in such direction without transmitting said secondr component of motion to said main slide when said driving member is rotated, and a pivotal and slidable connection between said proportioning device and said cross slide and responsive to rotation of said driving member through one revolution to transmit said second component of motion to the cross slide to move the latter along said second path through a second back and forth stroke of a length determined as a function of the diameter of said circular path and without transmitting said first component of motion to said cross slide.

27. In an ellipsograph, the combination of, a base, a slide guided on said base for back and forth translation along first and second mutually perpendicular paths, a marking element carried on and following the movement i v15 of said slide, a manually turnable actuator journaled-on said base to rotate about an axis and carrying a driving member normally spaced radially from said axis and rotatable in a circular path about said axis with a first component of motion in the general direction of said first path and with a second component of motion in the general direction of said second path, means connecting said driving member to said slide and transmitting said rst and second components of motion to the slide to move the latter along said rst path through a rst back and forth stroke and along said second path through a second back and forth stroke in response to rotation of said driving member through one revolution, each of said strokes being of a length determinable as a function of the diameter of said circular path, means mounting said driving member adjustably 0n said actuator and enabling selective movement of said driving member toward and away from said axis to permit changing of the diameter of l said circular path and the length of said first and second strokes by proportional amounts, means selectively adjustable by one manual operation to cause the transmission 0f any selected fraction ranging from Zero to one of one of the components of motion of said driving member to said slide and operable to change the length of the corresponding one of said strokes independently of the radial positioning of said driving member and without changing the length of the other stroke.

References Cited UNITED STATES PATENTS 184,493 11/1876v Anderson. 492,142 2/ 1893 Corkhill. 2,458,208 1/1949 Ruger 33-31 HARRY N. HAROIAN, Primary Examiner 

